Technical Field
The present invention relates to a detection device that detects fluorescence emitted from a label material labelling a detection object substance to detect the detection object substance.
Background Art
Highly sensitive and quantitative detection of a minute amount of a detection object substance such as protein and DNA in laboratory tests makes it possible to perform treatment by quickly determining the patient's condition. There is therefore a need for a detection device for quantitatively measuring a minute amount of detection object substance with high sensitivity.
A detection device utilizing surface plasmon-field enhanced fluorescence spectroscopy (hereinafter abbreviated as “SPFS”) is known as a detection device which can detect a detection object substance with high sensitivity (see, for example, PTL 1).
In the detection device disclosed in PTL 1, a sensor chip including a prism formed of a dielectric, a metal film formed on the prism, a capturing body (for example antibody) fixed on the metal film is used. When a sample containing a detection object substance is supplied on the metal film, the detection object substance is captured by the capturing body (primary reaction). The detection object substance thus captured is further labeled by a fluorescence material (secondary reaction). In this state, when the metal film is irradiated with excitation light through the prism at an angle at which surface plasmon resonance is caused, localized-field light can be generated on the surface of the metal film. With this localized-field light, the fluorescence material for labelling the captured detection object substance on the metal film is selectively excited, and fluorescence emitted from the fluorescence material is observed. In the detection device, the fluorescence is detected to detect the presence or the amount of the detection object substance.
The above-mentioned detection device uses highly sensitive light sensors such as a photomultiplier tube (PMT) and an avalanche photodiode (APD) to quantitatively detect weak fluorescence. In addition, a wavelength separation filter (wavelength selecting member) such as an interference filter and a color filter is used to detect weak fluorescence with a high S/N ratio. Further, a light guiding member having a columnar shape that condenses weak fluorescence is disposed at a position before the light sensor on the light path of the fluorescence. The fluorescence emitted from the fluorescence material is incident on one end surface (incidence surface) of the light guiding member, and is guided by being repeatedly reflected on the inside, and then emitted from the other end surface (emission surface). The wavelength separation filter included in the detection device removes various light rays other than fluorescence. Accordingly, only the fluorescence of the detection object reaches the light reception surface of the light sensor.